Space mapping of hip and wrists motions for different transfer distances in manual material handling task

Abstract

Manual material transfer tasks are common in occupational settings. Repetitive lifting tasks usually involve twisting and bending which are associated with occupational lower back injuries. One of the approaches to reduce bending and twisting is to separate the distance between lifting origin and destination, which will encourage lifters to step and turn entire bodies. However, adding lifting distances is likely to affect space usages and requirements. A study was conducted to investigate how the transfer distances influence space usage during the lifting task. Raw data of hip and hand wrists motion of 26 male subjects during transfer in 4 different distances were captured using X-Sens motion capture system. MVN Studio software was used to process and extract positional data. Tabulated space mapping revealed limited hip movement and semicircular shaped hand motions for short transfer distances. The pattern changes into a more stretched-curve shape as the distance increases. Overall, it was observed that shorter transfer distance caused participants to adopt more twisting and less bending postures, while further transfer distances resulted in more bending and less twisting. This study may provide industrial practitioners with information to design a space requirement for manual material transfer tasks.